1. Field of the Invention
This invention relates to a new class of transition metal containing linear polymers of varying molecular weight that are useful for conversion to high temperature thermosets and ceramics. These new materials have repeat units that contain alkynyl groups for cross-linking purposes along with organotransition metal complexes, silyl, siloxyl, boranyl, or di(silyl or siloxyl)carborane units. These novel linear polymers with the metal units in the backbone are soluble in most organic solvents and can be easily fabricated from the melt into shaped components, which enhance their importance for high temperature structural, magnetic, and microelectronic applications. Cross-linking of alkynyl groups is known to occur by either photochemical or thermal processes.
2. Technology Background
The incorporation of transition metals into a polymer structure has long been seen as a good way of preparing materials with different properties from conventional carbon-based polymers. Small molecule transition metal complexes and solid state compounds possess an array of interesting high temperature, hardness, redox, magnetic, optical, electrical, and catalytic properties. In addition, the rich diversity of coordination numbers and geometries available for transition elements offer the possibility of accessing polymers with unusual conformational, mechanical, and morphological characteristics.
The development of polymers with transition metals in the main chain structure would be expected to provide access to processable, specialty materials with similarly attractive physical properties that would be of interest as pyrolytic precursors to metal-containing ceramics. Transition metal-based polymers might also function as processable precursors for making metal-containing ceramic films and fibers with high stability and desirable physical properties. Most transition metal-based polymers reported to date, however, do not contain units for conversion to a thermoset and thus afford low char yields at elevated temperatures.
Despite early synthetic problems of constructing macromolecular chains, researchers have now prepared a variety of metal-containing polymers with novel properties. Ferrocene-based polymers appear to be particularly promising as reported by Ian Manners in Chain Metals, Chemistry In Britain, January 1996, pp. 46-49. Because of ferrocene""s ability to release and accept an electron reversibly, there is considerable interest in developing these materials as electrode mediators and in energy storage devices.
These mediators, for example, facilitate electron transfer between an enzyme such as glucose oxidase, where the redox active sites are buried in a protein sheath and an electrode. Ferrocene-based polymers have been successfully used as electron relays in electrochemical biosensors for measuring glucose levels. Scientists have also fabricated microelectrochemical devices such as diodes using ferrocene-based polymers.
Other studies have reported on the formation of Fexe2x80x94Sixe2x80x94C materials from the pyrolysis of iron containing polymers. See, for example: (1) Tang, B. Z.; Petersen, R.; Foucher, D. A.; Lough, A.; Coombs, N.; Sodhi, R.; Manners, I. J Chem. Soc., Chem Commun. 1993, 523-525; (2) Peterson, R; Foucher, D. A.; Tang, B. Z.; Lough, A.; Raju, N. P.; Greedan, J. E.; Manners, I. Chem. Mater. 1995, 7, 2045-2053; and (3) Ungurenasu, C. Macromolecules 1996, 29, 7297-7298; (4) Hodson, A. G. W; Smith, R. A. Transition Metal Functionalised Polysiloxanes as Precursors to Magnetic Ceramics, Faculty of Applied Sciences, University of the West of England, Bristol, BS16 1QY.
Spirocyclic [1]-ferrocenophanes have been reported to function as convenient cross-linking agents for poly(ferrocenes) via thermal ring-opening copolymerization reactions by MacLachlan, M. J.; Lough, A. J.; and Manners, I, in Macromolecules, 1996, 29, 8562-8564.
The use of ring-opening polymerization (ROP), a chain growth process, is reported by I. Manners in Polyhedron, Vol. 15, No. 24. pp 4311-4329, 1996 to allow access to a range of high molecular-weight polymers with skeletal transition metal atoms having novel properties.
Several poly(ferrocenylsilanes) have been synthesized and converted into ceramics upon heating to 1000xc2x0 C. under inert conditions. See, for example, Pudelski, J. K.; Rulkens, R.; Foucher, D. A.; Lough A. J.; MacDonald, P. M. and Manners, I., Macromolecules, 1995, 28, 7301-7308. The ceramic yields by thermogravimetric analysis (TGA), however, were in the range of 17 to 63%.
Alternative transition metals such as ruthenium have also been reported as being incorporated into a metallocenophane structure by Nelson, J. A.; Lough, A. J., and Manners, I in xe2x80x9cSynthesis and Ring-Opening Polymerization of Highly Strained, Ring-Titled[2]Ruthenocenophanesxe2x80x9d Angew. Chem., Int. Ed. Engl. 1994, 33, 989-991 and in xe2x80x9cSynthesis, Structures, and Polymerization Behavior of Di-silane-Bridged and Bis (disilane)-Bridged[2]Ruthenocenophanesxe2x80x9d in Organometallics 1994, 13, 3703-3710. Novel ruthenium or iron containing tetraynes as precursors of mixed-metal oligomers are reported in Organometallics 1996, 15, 1530-1531. Mixed valence diferrocenylacetylene cation compounds have been reported in the Journal of the American Chemical Society, 96:21, 1974, pp. 6788-6789.
The synthesis and characterization of linear boron-silicon-diacetylene copolymers is reported by R. A. Sundar and T. M. Keller in Macromolecules 1996, 29, 3647-3650. Additionally, the efficient, xe2x80x9cone-potxe2x80x9d synthesis of silylene-acetylene and disilylene-acetylene preceramic polymers from trichloroethylene is reported in the Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 28, 955-965 (1990).
Furthermore, the preparation and reactions of decachloroferrocene and decachlororuthenocene is disclosed in the Journal of the American Chemical Society, 95, 870-875 (1973). Symmetrically disubstituted ferrocenes are discussed in the Journal of Organometallic Chemistry, 27 (1971) pp. 241-249 as well as ferrocenyl-acetylene being disclosed in the J. Organometal. Chem., 6 (1966) pp. 173-180 and 399-411. Ferrocenyl- and 2-thienylarylacetylenes are reported by M. D. Rausch; A. Siegal and L. P. Kelmann in J. of Org. Chem. 1966, Vol. 31 p. 2703-2704.
Ferrocenyl ethylene and acetylene derivatives are also reported by P. L. Pauson and W. E. Watts in J. Chem. Soc. 1963, 2990-2996. Studies on the reactions of ferrocenylphenylacetylene and diferrocenyl-acetylene are reported in the Journal of Organometallic Chemistry, 149 (1978) 245-264. The chemistry of xcfx80-bridged analogues of biferrocene and biferrocenylene is discussed in the Journal of Organic Chemistry, Vol. 41, No. 16, 1976, 2700-2704. The synthesis of 1xe2x80x2, 6xe2x80x2-bis(ethynyl)-biferrocene and metal complexes referring to non-linear optics is presented in Polyhedron, Vol. 14, No. 19, pp. 2759-2766 (1995).
In addition to these documents discussing the various compounds and polymers, the catalytic graphitization by iron of isotropic carbon is reported in Carbon, Vol. 21, No. 1, pp. 81-87, 1983. Preceramic polymer routes to silicon carbide are disclosed by Richard M. Laine in Chem. Mater. 1993, 5, 260-279; and the comprehensive chemistry of polycarbosilanes, polysilazanes and polycarbosilazanes as precursors of ceramics is thoroughly reported in Chem. Rev., 1995, 95, 1443-1477.
U.S. Pat. Nos. 4,800,221 and 4,806,612 also respectively disclose silicon carbide preceramic polymers and preceramic acetylenic polysilanes which may be converted into ceramic materials.
U.S. Pat. Nos. 5,241,029 and 5,457,074 disclose diorganosilacetylene and diorganosilvinylene polymers which can be thermally converted into silicon carbide ceramic materials.
U.S. Pat. No. 4,851,491 discloses polyorganoborosilane ceramic polymers which are useful to generate high temperature ceramic materials upon thermal degradation. U.S. Pat. No. 4,946,919 also relates to boron-containing ceramics formed from organoboron preceramic polymers which are carboralated acetylenic polymers.
U.S. Pat. Nos. 5,272,237; 5,292,779; 5,348,917; 5,483,017 disclose carborane-(siloxane or silane)-unsaturated hydrocarbon based polymers reported to be useful for making high temperature oxidatively stable thermosets and/or ceramics.
U.S. Pat. No. 5,552,505 discloses copolymers formed from aromatic acetylenic monomers or prepolymers formed therefrom and carborane-(siloxane or silane)-unsaturated hydrocarbon polymers reportedly useful to form articles, adhesives, matrix materials, or coatings, or which may be pyrolyzed to form carbon-ceramic composites. Each of the documents cited herein contains valuable information and each is incorporated herein by reference in its entirety and for all purposes.
Most of the carborane-siloxane and/or carborane-silane polymers made by others have elastomeric properties rather than properties of more rigid polymeric products like thermosetting polymers or ceramics. There is a need for polymers that behave less like elastomeric polymers and more like thermosets and which, upon pyrolysis, form ceramics.
There is, therefore, a need for oxidatively stable materials having thermosetting properties for making rigid components therefrom which withstand high temperatures and which have high strength and high hardness properties and/or which optionally may have magnetic properties.
Furthermore, there is a need for transition metal-based polymers which contain units for conversion to thermosets and which afford high char yields at elevated temperatures. There is also a need for such polymers which would be useful precursors to novel materials unavailable from other sources, and which may exhibit unique nonlinear optical (NLO) properties.
It is therefore an object of the present invention to provide polymers having backbones incorporated with organotransition metals complexes along with silicon, acetylenic, and/or boron units which are useful as precursors to novel materials unavailable from other sources.
It is another object of the present invention to provide polymers having backbones incorporated with organotransition metal complexes along with silicon, acetylenic, and/or boron units which can be readily converted into high temperature thermosets.
It is another object of the present invention to provide polymers having backbones incorporating organotransition metal complexes along with silicon, acetylenic, and/or boron units which can readily be converted into high temperature materials which exhibit high strength properties, high hardness values, and electrical and/or magnetic properties.
It is yet another object of the present invention to provide transition metal based polymers which contain inorganic units and units for conversion to thermoset polymers and which afford high char yields at elevated temperatures.
It is still another object of the present invention to permit the formulation of ceramics containing a variable and controllable amount of metal and various cluster sizes.
These and other objectives are accomplished by first forming polymers having the following general composition: 
wherein:
x is greater than or equal to one;
z is greater than or equal to one;
w is greater than or equal to one;
y is greater than or equal to one;
a is greater than or equal to one;
R1, R2, R3, R4, R5, R6, R7, and R8 may be the same or different and wherein each equal H, unsubstituted or substituted hydrocarbon moieties, unsubstituted or substituted alkyl or arylamino moieties; unsubstituted or substituted alkyl or aryl phosphino moieties; halogen;
M=Fe, Ru, Os, or a combination thereof; and
E is 
xe2x80x83wherein:
f is greater than or equal to zero;
g is greater than or equal to one;
h is greater than or equal to one;
p is greater than or equal to zero;
q is greater than or equal to zero;
s is greater than or equal to zero and is greater than or equal to one when q is greater than or equal to one;
t is greater than or equal to zero
k=3 to 16;
R9, R10, R11, R12 may be the same or different and wherein each=H, unsubstituted hydrocarbon moieties or substituted hydrocarbon moieties; and
R13=unsubstituted or substituted hydrocarbon moieties.
As suggested above, R1 through R13 may each be one of any monovalent organic group, or, in the case of R1-R12, may be hydrogen. R1 through R13 may be aromatic, aliphatic, or include both aliphatic and aromatic moieties. R1 through R13 may be saturated or include unsaturation. In all cases, R1 through R13 may be halo-substituted. The carborane may be ortho meta or para.
Also, throughout the specification and claims, it should be understood that the value of E, and its associated variables, may differ at each occurance of E within the polymer, within the definitions provided for E and its associated variables. Thus, throughout the specification and claims, it should be understood that E and the variables included therein do not represent singular and constant values throughout the polymer. Instead, E and the variables included therein represent values that may vary, within the proscribed limits, throughout the polymer.
Typical groups for R9-R12 are, for example, hydrogen, methyl, ethyl, n-propyl, isopropyl, phenyl and tolyl. More often, R9-R12 are hydrogen, methyl, or ethyl. Most often R9-R12 are hydrogen or methyl.
Typically, R13 is methyl, ethyl, n-propyl, isopropyl, and the like, or phenyl, tolyl, and the like; most typically wherein R13 is methyl, ethyl or phenyl.
A typical xe2x80x9cExe2x80x9d component may have k=3 to 12; a more typical xe2x80x9cExe2x80x9d component having k=5 to 10; the even more typical xe2x80x9cExe2x80x9d component having k=8 to 10; and the most typical xe2x80x9cExe2x80x9d component having k=10.
Typical ranges for xe2x80x9cfxe2x80x9d include 0 to 10; more typically 0 to 6; and most typically from 0 to 2.
Typical ranges for xe2x80x9cgxe2x80x9d include 1 to 10; more typically 1 to 6; and most typically from 1 to 2.
Typical ranges for xe2x80x9chxe2x80x9d include 1 to 50; more typically 1 to 20; and most typically from 1 to 5.
Typical ranges for xe2x80x9cpxe2x80x9d include 0 to 50; more typically 0 to 20; and most typically from 0 to 5.
Typical ranges for xe2x80x9cqxe2x80x9d include 0 to 10 more typically 0 to 4; and most typically from 0 to 2.
Typical ranges for xe2x80x9csxe2x80x9d include 0 to 10; more typically 1 to 6; and most typically from 1 to 2.
Typical ranges for xe2x80x9ctxe2x80x9d include 0 to 10; more typically 0 to 6; and most typically from 0 to 2.
Typical ranges for xe2x80x9cwxe2x80x9d in these organometallic polymers, thermosets, and ceramics are from 1 to 100; more typically from 1 to 50; more often typically from 1 to 20; even more often from 1 to 10; and most often 1 to 3.
Typical ranges for xe2x80x9cyxe2x80x9d in these organometallic polymers, thermosets, are from 1 to 100; more typically from 1 to 50; more often from 1 to 20; even more often 1 to 10; and most often 1 to 3.
Typical ranges for xe2x80x9czxe2x80x9d in these organometallic polymers, thermosets, and ceramics are from 1 to 100; more typically from 1 to 80; more often from 1 to 50; even more often 1 to 30; and most often 1 to 20.
Typical xe2x80x9cMxe2x80x9d components of these novel organometallic polymers, thermosets and ceramics include transition metals; more typically being Fe, Ru, Os or combinations thereof; most typically being Fe, Ru or combinations thereof; most preferred being Fe. Different amounts of iron can be added to these polymers, thermosets, and ceramics depending on the additive compounds or combination of compounds, for example, ferrocene, biferrocene, triferrocene, and the like may be incorporated. Typically xe2x80x9caxe2x80x9d in these polymers, thermosets and ceramics may range from 1 to 20; more typically being from 1 to 10; more often being from 1 to 8; even more often being from 1 to 5; most often being from 1 to 3.
It should be understood that the general formula for the polymers describes both random and block copolymers. Throughout the specification and the claims that follows, the general polymer formula provided above will be used to represent a polymer having the structural elements shown, independent of the nature of the terminal groups. It should be further understood that a group described as xe2x80x9csubstitutedxe2x80x9d may be, for example, halo or haloalkyl substituted, unless otherwise explicitly stated.
The following general reaction represented in Scheme 1 illustrates the synthesis of the metallocene polymers containing acetylenic and inorganic units; the formation of thermosets therefrom; and the ultimate formation of the novel ceramics. In Scheme 1, X is a leaving group, such as a halogen, tosylate, and trifluoromethane sulfonate. Where EX2 in Scheme 1 is a mixture of various compounds in which E and X meet the above-provided definitions, E and its associated variables will have different values at different occurances within the polymer. Of course, each E, and its associated variable within the polymer, will meet the definitions provided for them in the present application.

wherein all variables are as described above.
Throughout the specification and claims, it should be understood that the the structure 
represents a complex structure consisting of a plurality of cross-linked acetylenic moieties. The structure shown is not intended to be representative of the actual cross-links existing within that structure. In reality, the cross-linked acetylenic moiety may include several different cross-linking structures such as those shown below: 